Does the % drop really matter that much? No one really knows how much it will drop. 50% off peak gets tossed around alot.
Now different areas had differnt peaks, so the remaining % drop in Del Mar will not be the same as the % drop in Chula Vista. Why? Cause the % increase wasnt the same either. So % drop in NC coastal or SC inland? Or how about Oside drop vs La Jolla? Both are NCC, but they dont relate to each other much. It wont be the same everywhere, cause the fundamentals and demographics are totally different.
The real point is that the market is tanking in a way that is historically unpresidented. To assume that comparisons to previous well presidented busts is, well, to assume. The Market is going down, and it will continue for a while. This bubble took alot longer then 18 months to inflate, and itll take longer to deflate too.
If you want a percentage, take your area of interset, find out the underlying fundamentals (ie income, interest rates, age, views, etc. (you can usually assume 2000-01 prices isnt far off)) and then extrapolate from there. Some will have farther to go than others, but all are still going DOWN and will continue to do so for some time. Do you really need to know more than that?